CVE-2026-19813

Name of the Vulnerable Software and Affected Versions TOTOLINK A800R version 4.1.2cu.5137 B20200730

Description A remote stack-based buffer overflow exists within the firewall.so component. The issue occurs in the setMacFilterRules() function located in the /cgi-bin/cstecgi.cgi endpoint when the Comment variable is manipulated. A stack-based buffer overflow is a condition where a program writes more data to a buffer located on the stack than the buffer is allocated to hold, potentially leading to crashes or arbitrary code execution.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability. As a temporary workaround, restrict access to the /cgi-bin/cstecgi.cgi endpoint to minimize the risk of exploitation.